1. Field of the Invention
The present invention relates generally to the field of power assisted steering systems for automotive vehicles and more particularly to such a system employing a torque responsive control mechanism for controlling the operation of a servomotor.
2. Description of the Prior Art
In known power assisted steering systems a valve body is generally formed integrally with the pinion of the system and the torsion bar is formed as a separate element from the valve body and pinion. One end of the torsion bar is generally connected to the valve body by means of a pin and the other end of the torsion bar is connected to the steering shaft. In this type of construction, a substantial gap must be provided between the pinion and the valve body so as to prevent the valve body from being damaged by the cutter during the formation of the pinion teeth. As a result, the control valve and piston member have an excessive overall axial length. In addition, any heat treatment provided in order to improve the characteristics of the pinion should be isolated from the valve body thereby necessitating greater axial length of the combined valve body and pinion.